Compositions from coal tar and higher fatty acid chlorides and process of making thesame



'the generic formula. RCOCl.

Patented Mar. 10, 1936 UNITED STATES PATENT OFFICE COMPOSITIONS FROMCOAL TAB AND HIGHER FATTY ACID CHIDRIDES AND PROCESS OF MAKING THE SAMEration of Illinois No Drawing. Application July 1, 1935, Serial No.29,422

19 Claims.

This invention relates to useful products derived from coal tardistillates and higher fatty acids, and processes of preparing the same;and it comprises compositions which are the products of reacting coaltar fractions with higher fatty acid chlorides in the presence ofaluminum chloride by a Friedel-Crafts synthesis, these compositionsbeing oily, viscous liquids, or wax-like solids, of unknown chemicalconstitution; and it further comprises processes wherein a coal tarfraction composed of a mixture of substances derived from coal tar bydistillation or extraction is reacted with a higher fatty acid chloridein the presence of aluminum chloride by a Friedel- Crafts synthesis.

The higher fatty acids having six or more atoms of carbon are cheap andabundant materials. They are the normal constituents in animal andvegetable fats and they can be obtained from such fats at relativelylittle expense. These higher fatty acids havc been used almostexclusively in the soap industry for making candles, etc., and inrelatively few instances have they been used as reagents in chemicalreactions in what might be termed the fine organic chemical field.

We have now discovered that valuable compounds can be made from thesehigher fatty acids when in the form of their acid chlorides. We havediscovered that higher fatty acid chlorides will react with coal tardistillates or fractions in the presence of aluminum chloride to giveproducts which are useful in many relations. The products which weobtain vary from rather viscous oils to solid wax-like materials. Wefind that these products are extremely useful as addition agents to beadded to lubricating oils, and this discovery has been separatelydescribed and claimed in an application in the names of Ralston,Christensen and Selby filed of even date herewith.

In broad aspects our invention comprises reacting a higher fatty acidchloride with a coal tar distillate, or with acid or basic fractions ofsuch a distillate, in the presence of aluminum chloride by theFriedel-Crafts reaction. In the practice of our invention we can use asstarting materials any acid chloride of a higher fatty acid. Thesehigher fatty acid chlorides all have of the class of acid chlorides,acetyl chloride is one of the lowest members, but our invention relatesonly to the use of acid chlorides derived from higher fatty acidscontaining at least six carbon atoms beginningwith caproic. Hence, inour invention we can use caproyl chloride, capryl chloride, laurylchloride, myristyl chloride, palmityl chloride, stearyl chloride andalso the acid chlorides corresponding to arachidic, behenic, carnaubic,cerotic, and melissic acids. We can also use higher fatty acid chloridesderived from unsaturated fatty acids such as oleic and linoleic. In mostinstances we use mixtures of various fatty acids. One common mixtureoccurring in nature is a mixture of stearic and palmitic acid. Such amixture can be obtained by saponifying fats and treating the soaps thusformed with hydrochloric acid to liberate the free fatty acids. Thismixture of free fatty acids can then be converted to a mixture of higherfatty acid chlorides by means of phosphorous pentachloride.

In the practice of our invention we can use both liquid and solidfractions of coal tar and we generally begin with those fractions ordistillates boiling from 200 C. upward. The fractions, distillates, orextracts which we use are generally mixtures of various aromatic andheterocyclic hydrocarbons, phenols, creosols and other substances ofcomplex structure. One 'of the most desirable coal tar fractions for usein our process is that known as red wax. Red wax is a solid waxymaterial obtained from distilling coal tar pitch. The red wax is afraction boiling between about 432 C. and 500 C.

Ordinarily we do not use coal tar fractions or distillates boiling belowabout 200 C. except-in the case of coal tar bases to be described; andwe do not, in the present invention, react pure constituents of coal tarsuch as pure naphthalene or anthracene wth higher fatty acid chlorides.Many of the coal tar distillates which we use in our invention containquantities of naphthalene and anthracene admixed with otherhydrocarbons, phenols, creosols, and the like, and our invention dealsparticularly with the treatment of these mixtures and not with pureconstituents thereof. Many of the desirable characteristics in theproducts which we obtain are due to the fact that these products aremixtures of substances, and not pure chemical compounds and it isaccordingly advantageous that we react higher fatty acid chlorides withcoal tar fractions, distillates or extracts containing a plurality ofcompounds, rather than with pure chemical individuals.

We shall now describe our invention with specific reference to preparingproducts from many different coal tar fractions. In order to keep ourdisclosure within reasonable bounds we shall restrict our specificexamples to the use of stearyl chloride. This acid chloride can be madefrom stearic 'acid readily and it is a chloride which we ordinarily usein the practice of our invention. It is to be understood, however, thatall of the higher fatty acid chlorides enumerated above can be usedinstead of stearyl chloride.

Before proceeding further it will be helpful if a brief outline of coaltar distillation products is presented. When coal tar is distilled, thefirst fraction, or cut, boiling up to about 200 C., is known as light"oil. We do not, in our invention, ordinarily use this fraction, althoughwe can prepare useful products from light coal tar bases, about 30 percent of which boils below 200 C. These will be described presently. Thenext fraction obtained in the distillation is known as middle oil and itboils from 200 to 250 C. The next highest cut, called heavy" oil, boilsfrom 250 to 300 C. The so-called anthracene oil fraction, which consistslargely of crude anthracene and some naphthalene, boils from 300 to 350C. If the distillation of the tar be stopped at this point the residuein the still is known as pitch. The pitch can be further distilled,however, to give another heavy oil boiling from about 360 to about 432C. and red wax a waxy solid, boiling from 432 to 500 C. What is left inthe still is now essentially carbon or coke. In our invention we can useany of the distillates boiling above 200 C. obtained by distilling thecoal tar and the pitch. In other words we use coal tar fractions boilingfrom 200 to 500 C. We can also use products obtained from thesefractions by extracting them with acids or bases as will presently bedescribed.

We shall now first refer to products obtained by reacting so-calledcrude tower bottoms with stearyl chloride. These crude tower bottomshave a boiling point range of about 230 C. to 375 0. They comprise apart of the heavy oil out, the anthracene oil out and a portion of theheavy oil obtained from the pitch. The exact composition of these crudetower bottoms is not known. They contain anthracene, naphthalene,phenols, creosols, and probably many other substances.

We first prepare a mixture of about 35 parts by .weight of the towerbottoms, 73 parts by weight of stearyl chloride, and 258 parts by weightof carbon disulphide. To this mixture we add, at room temperature, 67parts by weightof aluminum chloride over a period of three hours. Themixture is then refluxed for about two hours at 46 C. and then'pouredupon a mixture of ice and hydrochloric acid. The mixture is then steamdistilled, this resulting in the hydrolysis of a complex aluminumcompound probably analogous to the usual type of compounds obtained inthe Friedel-Crafts synthesis. When the hydrolysis is complete theproduct obtained will appear as a reddish-brown, free-flowing oilfloating on the surface of the aqueous mixture of aluminum chloride.Hydrolysis should be continued until this oily reaction product issubstantially free of aluminum. Should it be difficult to remove alltraces of aluminum, we find it advantageous to treat the oily reactionproduct with a mixture of acetone and hydrochloric acid under a refluxuntil the oily liquid becomes aluminum free. In most instances it isunnecessary to use an acetone-hydrochloric acid mixture since steamdistillation ordinarily effects complete hydrolysis.

The chemical composition of this reaction product is not clearlyunderstood. It probably contains ketonic compounds derived fromanthracene and stearyl chloride. But, since phenols and creosols arealso present in the initial coal tar fraction, it is apparent that thefinal reaction products are probably quite complex.

The reddish-brown, free-flowing oil is useful in a number of relations.It has a rather high dielectric constant and can be used in transformeroils. When added to lubricating oils it imparts oiliness to the oil andalso lowers the pour point. As noted above this discovery forms thesubject matter of a copending application. We can vary the ratios oftower bottoms to stearyl chloride over a wide range. For example, we canuse 70 parts of tower bottoms and 73 parts of stearyl chloride,following the same general procedure indicated above, and as a result weget an oil which is dark brown and somewhat more viscous than thatobtained in the first example described above.

In each instance we conduct the process steps of our invention in themanner described above for crude tower bottoms. Accordingly we will notspecifically describeall of these steps in connection with each of thefractions of coal tar which we can treat and shall now describe.

Instead of beginning with the crude tower bottoms we can start withfractions thereof. In the following table we summarize examples usingvarious fractions of the crude tower bottoms.

Fractions from crude tower bottoms Cut C. Character of product 215-245Dark brown viscous oil 245-320 Reddish-brown viscous oil 300-315Reddish-brown viscous oil 315-330 Viscous dark brown oil 330-345 Darkbrown grease 345-365 Reddish-brown oil Residue Tarry mass In each ofthese examples tabulated above 35 parts by weight of the cut, or thetower bottom residue, were mixed with 73 parts by weight of stearylchloride. In most cases the amount of carbon disulphide was about 400parts by weight, this not being critical, and it acting only as solventor diluent. In each instance 67 parts by weight of aluminum chloridewere used.

We shall now describe a further modification of our invention wherein weuse as starting materials the acidic or basic constituents of crude tarbottoms and also the residue left after washing the crude tower bottomswith an alkali, an acid, or both.

Thus, for example, we wash or extract the crude tower bottoms with a 20percent solution of sodium hydroxide, using several portions of thecaustic soda until the extracted material appears to be acid free. Thealkali-washed tower bottoms are then dried and used as startingmaterial. When 35 parts by weight of the alkali-washed tower bottoms(that is, the tower bottoms freed of alkali-soluble constituents) arereacted with 73 parts by weight of stearyl chloride in accordance withthe above, the product is a greenishbrown, viscous oil which markedlylowers the pour point of a lubricating'oil. In a similar way we canneutralize the aqueous alkaline extracts with an acid, thus liberatingthe alkali-soluble products extracted from the tower bottoms, and reactthem with stearyl-chloride. With a ratio of 35 parts of thealkali-soluble constituents to 73 parts of stearyl chloride we obtain areddish,

, I 2,038,545 free-flowing oil which will lower the pour point of alubricating oil markedly .1

In a similar way we extract the crude tower bottoms with 40 percentsulphuric acid solution at room temperature. The dried, acid-washedtower bottoms give, when reacted with stearyl chloride in theproportions noted immediately above, a light reddish-brown grease. Theacidsoluble portions of the tower bottoms can be used provided the acidextraction liquor containing them is first neutralized to liberate itscontent of acid-soluble constituents and these are washed and dried.When 35 parts of the acid-soluble constituents are reacted with 73 partsof stearyl chloride we obtain a brown, waxy solid useful in waxingcompositions and in lubricating oils.

We can also extract the tower bottoms first with 20 percent sodiumhydroxide solution to remove alkali-soluble constituents and thenwith 40percent sulphuric acid solution to remove acidsoluble constituents. Theextracted residue gives a dark red, waxy, free-flowing oil when reactedwith stearyl chloride as described above.

We shall now describe a further modification of our invention in whichwe start with a coal tar distillate known as "red wax". This material isa distillate having a boiling point range of approximately 432 to 500 C.It represents approximately 7 percent of the coal tar and is the highestboiling distillate obtainable. As it occurs in commerce it is a mixtureof highly condensed aromatic compounds of complex, unknown structure.

Red wax is especially advantageous in' our invention since it gives -usproducts having many desirable characteristics.

When using red wax as a starting material we mix from 5 parts by weightto 140 parts by weight of red wax with about '73 parts by weight ofstearyl chloride, and from 129 parts by weight to 1,032

parts by weight of carbon disulphide. The higher quantities of red waxrequire more solvent for reaction purposes. In each instance we useabout 6'7 parts by weight of alminum chloride and the Friedel-Craftsreaction is conducted in the same manner as that described for crudetower bottoms.

This procedure gives usproducts varying from a yellowish-red,free-flowing oil to a hard, dark red, waxy solid. We find that the bestproportions of red wax to stearyl chloride are 1 to 1 or 2 to 1. A ratioof 1 to 1 gives us a soft red wax having an exceedingly desirable pourpoint lowering characteristic when added to a lubricating oil. A ratioof 2 to 1 gives us a reddish-brown, sluggish-flowing oil alsoparticularly useful as an addition agent for lubricating oils.

We can also extract alkali and acid soluble constituents from the redwax in the manner described above for the extraction of such substancesfrom crude tar bottoms. For example we extract red wax with a 40 percentsulphuric acid solution to remove acid-soluble compounds. Thisacid-washed red wax residue, now free of acidsoluble compounds, willgive a rubber-like solid material when reacted with stearyl chloride inthe proportions of 9 to 18 parts by weight of extracted red wax and 73parts by weight of stearyl chloride. When the quantity of acid washedred wax is increased to 35 parts by weight the product is a dark red waxwhich, when added to a lubricating oil, will reduce itspour point.

The acid washings from the acid extraction of the red wax also contains.substances which will react with stearyl chloride. For example weneutralize the acid washings with sodium hydroxide,. extract theacid-soluble constituents with ether, evaporate the ether, and react 35parts of these acid-soluble constituents with 73 parts of stearylchloride. The product is a dark red, rather hard wax.

We can also use high boiling fractions of red wax. For example we reacta fraction boiling from 450 to 500 C. with stearyl chloride and getproducts varying from a rubbery material to a heavy, dark red oil.

We find that many of these substances when added to lubricating oilstend to darken the oil. This disadvantage, while not serious, can beobviated by subjecting the oily wax-like products to the action of soliddecolorizing substances such as Filtrol and Netrol or otherdecolorizingagents of the activated carbon or clay type.

In a still further modification of our invention we can start with crudeantharcene. This is a material containing approximately 40 percentanthracene, the rest being naphthalene, methyl naphthalene, carbazol,fluorene, phenanthrene and other substances. When we react 35 parts ofcrude anthracene with 73 parts of stearyl chloride we obtain a red, waxymaterial containing appreciable amounts of naphthalene and anthracene.Much of these impurities can be removed by distillation and the somewhatpurified red, waxy material markedly lowers the pour point of alubricating oil. It is also useful in many other relations, particularlydielectrics.

In a similar manner we can use crude anthracene which has been subjectedto an acid extraction with sulphuric acid to remove basic constituents,and in these cases we get products which are dark red, highly viscousoils or brownish-red, soft, greasy wax-like materials depending on theratio of acid-washed crude anthracene to stearyl chloride. As thequantity of acidwashed anthracene increases the product tends to be moresolid and wax-like.

In a further modification we use various coal 1 tar fractions boilingfrom 300 to 500 C. but of rather wide boiling point range. For examplewe react a coal tar distillate (35 parts) boiling range of 300 to 375 C.with '73 parts of stearyl chloride and obtain a free-flowing oil.Another coal tar distillate, boiling range 400 to 500 C.,

' will give a red, highly viscous oil when reacted with sulphuric acid.The material we start with has a boiling point range of from 100 to 355C., per cent of it distilling above 200 C. One part of this by weightand two'parts of stearyl chloride yields a dark red greasy solid.

We can also use the so-called heavy coal tar bases, which have adistillation range of about 100 to 391 C. but with more than percentboiling above 200 C. One part of the heavy bases to two parts ofstearylchloride gives dark red greasy solids which markedly lower thepour point of a lubricating oil. The ratio of bases to stearyl chloridecan be varied over a wide range from' about one to four parts of basesto one part of higher fatty acid chloride.

In a further modification of our inventionwe can use creosote oilresidues. These residues are commercial products and consist mostly ofcreosote and higher homologues of creosote. These residues are all veryhigh boiling, the boiling point range being from about 150 to 250 C. atmm. pressure. They can also be described as an overhead distillateobtained from the alkalisoluble portions of coal tar. But in connectionwith these materials we do not wish to be limited to coal tar as theonly source of them. Similar creosote oil residues are obtained fromwood tar or petroleum oil of certain kinds. Accordingly in the appendedclaims by "creosote oil residues" we mean to include materials of thiskind regardless of their source.

Fifty parts by weight of creosote oil residues, when reacted with '73parts by weight of stearyl chloride, will give a brown, viscous tar-likematerial markedly lowering the pour point of a lubricating oil whenadded thereto in small amounts.

Instead of using the creosote oil residues as such we can use variousfractions thereof. For example, we divide the creosote oil, bydistillation. into four fractions, the first of which boils up to 150 C.at 10 mm., the second from 150 to 200 C., the third from 200 to 230 0.,all at 10 mm., and the fourth being the residue after the distillation.All of these fractions will react with higher fatty acid chlorides inthe presence of aluminum chloride to yield products varying fromreddish-brown oils to reddish-brown, waxlike mixtures.

In the foregoing disclosure of our invention we have described manydifferent fractions, distillates, and extracts of coal tar which we canuse. In order to keep the description within reasonable limits we haveomitted operating details in many instances. In every case, however, thecoal tar distillate, or extract, and the higher fatty acid chloride isdissolved in carbon disulphide or otherorganic solvent customarily usedin the Friedel- Crafts reaction. The mixture is then cooled or kept atabout-room temperature during the addition of aluminum chloride, whichof course functions in the well-known way. In general the amount ofaluminum chloride is practically the same as the amount of .stearyl orother higher fatty acid chloride. After the reaction is completed thecomplex aluminum compound is hydrolized with a mineral acid, the excesssolvent steam distilled from the reaction mixture, and the productrecovered, usually as an oily material or a wax-like solid. We are not,of course, to be limited to the proportions stated since these can bevaried materially.

Although we have more specifically referred to the use of our productsin lubricting oils to impart oiliness thereto, and to modify the pourpoint of the oil, it is to be understood, that our products have manyother uses. Many of them are good dielectric materials. Others can beused in waxing and polishing compositions, as water-proofing materials,and in other relations.

In the appended claims we are obliged to define our products byreference to the process of making them since we do not know the exactchemical constitution of them. We do know that they are all mixtures ofsubstances, possibly ketonic, possibly condensed higher hydrocarbons,and various heterocyclic compounds especially in the case of productsmade from coal tar bases. And, in the appended claims, the term"fraction" is intended to cover distillates and extracts broadly.

Having thus described our invention, what we claim is:

1. The process which includes reacting by a Friedel-Crafts synthesis acoal tar fraction, the major portion of which boils above about 200" C.,with a fatty acid chloride having at least six carbon atoms in thepresence of aluminum chloride.

2. The process as in claim 1 wherein the acid chloride is stearylchloride.

3. The process which includes reacting by a Friedel-Crafts synthesis acoal tar distillate, the major portion of which boils above 200 C., witha fatty acid chloride having at least six carbon atoms in the presenceof aluminum chloride.

4. The process asin claim 3 wherein the acid chloride is stearylchloride.

5. The process which includes reacting by a Friedel-Crafts synthesis acoal tar fraction chosen from the group consisting of alkali-soluble andacid-soluble portions of coal tar with a fatty acid chloride having atleast six carbon' atoms in the presence of aluminum chloride.

6. The process as in claim 5 wherein the acid chloride is stearylchloride.

7. The process which includes reacting by a Friedel-Crafts synthesis acoal tar fraction boiling within the range 200 C.-500 C. with a fattyacid chloride having at least six carbon atoms in the presence ofaluminum chloride.

8. The process as in claim 7 wherein the acid chloride is stearylchloride.

9. The process which includes reacting by a Friedel-Crafts synthesis thecoal tar fraction having a boiling point range of about 432 C. to 500 C.with a fatty acid chloride having at least six carbon atoms in thepresence of aluminum chloride.

10. The process as in claim 9 wherein the acid chloride is stearylchloride.

11. The process which includes reacting by a Friedel-Crafts synthesisheavy coal tar bases with a fatty acid chloride having at least sixcarbon atoms in the presence of aluminum chloride.

12. The process which includes reacting by a Friedel-Crafts synthesiscrude anthracene with a fatty acid chloride having at least six carbonatoms in the presence of aluminum chloride.

13. The Friedel-Crafts reaction product from a fatty acid chloridehaving at least six carbon atoms and a coal tar fraction, the majorportion of which boils above about 200 C.

14. The Friedel-Crafts reaction product from a fatty acid chloridehaving at least six carbon atoms and a coal tar distillate, the majorportion of which boils above about 200 C.

15. The Friedel-Crafts reaction product from a fatty acid chloridehaving at least six carbon atoms and a coal tar fraction chosen from thegroup consisting of alkali-soluble and acid-soluble portions of coaltar.

16. The Friedel-Crafts reaction product from a fatty acid chloridehaving at least six carbon atoms and the coal tar fraction having aboiling point range of about 432 C. to 500 C.

17. The Friedel-Crafts reaction product from a. fatty acid chloridehaving at least six carbon atoms and heavy coal tar bases. I

18. The Friedel-Crafts reaction product from a fatty acid chloridehaving at least six carbon atoms and crude anthrace'ne.

19. The Frledel-Crafts reaction product from stearyl chloride and thecoal tar fraction having a boiling point range of about 432 to 500 C.

